EDIT: Sorry, I misunderstood the question and thought you were going to upgrade the host
If the update is interrupted in your VM, and it isn't able to resume, you might have to do a
sudo apt-get install -f
to resolve some dependency issues before continuing with
sudo apt-get dist-upgrade
If the dist-upgrade is still in the stage of downloading the new packages, I would simply stop it by issuing
C. The already downloaded packages stay in apts cache and there won't be any unresolved conflicts.
Old answer (thought OP is upgrading the host system):
That won't be a problem - the virtual system is isolated from the host system and has no clue if there was an upgrade.
However, you might have to update the guest additions in your virtual system to ensure nice integration with the host.